In all honesty as a white south african who has researched into this. Nothing it would be a speed bump, the white south africans would likely be larger, due to no Second War. However there wouldnt be a migration to Namibia, as it was physically impossible, and was attempted once or twice, leading to the deaths of those involved in the northern Kalahari. And to any involved in the 1st Boer War we were basically proto-Nazis, the treaty that ended the war stipulated that our republics had to abolish slavery, this was after the Brazilians, OTL. This isnt to say that the british were saints, by no stretch of the imagination were they saints but definitely the actions of the south africans was questionable at best.